Devices for performing treatment by irradiating a treatment target with light such as a laser have previously been proposed. For example, laser treatment devices which serve as devices for treating a treatment target such as a port wine stain, strawberry mark, and telangiectasia so-called vascular lesions are available, and perform treatment by irradiating vascular lesions with a laser (see Japanese Patent Application Publication No. 2005-237963 and Japanese Patent Application Publication No. H08-126712, for example).